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Arthritis Arthritis Treatment

Glucosamine May Help Arthritis Pain, but Do Supplements Contain Enough of It?

A popular supplement that is said to rebuild cartilage in sore joints may be less potent than believed, a new study suggests. Researchers at Tufts-New England Medical Center found that only a small portion of glucosamine is absorbed by the body, meaning that the typical doses sold over-the-counter are probably not strong enough to help achy knees and hips.

The findings, which will be published next month in the Annals of Rheumatic Disease and are currently posted on the journal's Web site, do nothing to undermine the pain relief claims of glucosamine. Still, they raise new doubts about how much glucosamine is needed to provide a benefit.

"Higher doses might work, but then there's the question of safety," said Dr. Timothy McAlindon, a researcher at Tufts who helped conduct the study.

Glucosamine, a type of sugar found naturally in the body, is thought to play a role in building cartilage, the spongy tissue that gradually breaks down in arthritic joints. Rare for an alternative therapy, glucosamine supplements have been tested in several rigorous clinical trials, where they've generally outperformed placebos in relieving pain.

Intriguingly, lab experiments suggest that taking glucosamine supplements can also repair the damage to joints, an upshot that no other osteoarthritis treatment appears to have. Many patients have embraced the supplements as a substitute for prescription drugs, and a growing number of doctors now recommend glucosamine as part of their routine care.

But until the current work, McAlindon said, no one had tested whether glucosamine supplements were absorbed at a strength that could do the most good.

As part of the study, McAlindon and colleagues looked at 18 patients who took 1,500 milligrams of glucosamine for their osteoarthritis. Using a powerful new blood test, they found that supplements are rapidly broken down in the liver, leaving just a minuscule amount of glucosamine to make its way to the joints.

At best, some patients had about 11 micromoles of glucosamine circulating in their blood several hours after taking the pills. Yet previous studies suggest that it may take glucosamine concentrations of about 10 times that amount to rebuild cartilage. Even at the highest concentration, the typical supplement would contribute only a small percent of the glucosamine needed to build stronger joints.

Taking higher doses of these supplements might increase glucosamine levels to the point needed to fight arthritis, but McAlindon warned that getting too much of this sugar may raise the risk of diabetes. Further studies due out later this year should help clarify the right dose to take.

In the meantime, McAlindon said that patients are probably safe in using small amounts of glucosamine, as long as they don't mind the risk of wasting their money.

"The main injury is primarily to the wallet," he said.